The present invention relates to a copying machine having an interrupt function.
In copying machines, copying paper sheets are fed from paper feed cassettes detachably mounted on a main body so as to copy documents of various sizes or to copy a document by various magnifications. The paper feed cassettes are made so as to correspond to sizes of the paper sheets. Thus, one copying machine can use copying paper sheets of various sizes. Generally, upper and lower paper feed cassettes can be loaded in the copying machine so as to save the trouble of replacing the paper feed cassette every time the size of the paper sheet is changed. Either one of the cassettes is selected by a cassette selector switch provided on an operation panel. In the copying machine of this type, one of the cassettes must be selected before starting the copying operation.
Furthermore, in a copying machine, a copying number, copying magnification and copying density can be set to be shifted from respective reference values. Therefore, before starting the copying operation, a size of the copying paper, copying number, copying magnification and copying density and the like (to be referred to as copying instructions hereinafter) must be set.
Meanwhile, in recent copying machines, an interrupt function is provided for interrupting the current copying operation to copy a document which is needed first. When the interrupt copying mode is set, the copying instructions of the current copying operation are temporarily stored in a memory. Thereafter, the copying instructions for the interrupt copying mode can be set. When the interrupt copying mode is completed, the former copying instructions are read out from the memory, thereby restarting the copying operation which was interrupted.
When the interruption copying mode is set, the copying instructions are automatically set to be the same as those of an initial state. That is, the paper feed cassette (a size of the copying paper) is set as the upper paper feed cassette, the copying number is set to be 1, the copying magnification is set at the equal mode, and the copying density is set at the automatic setting mode (i.e., an exposure amount is changed in accordance with a density of a document, thereby keeping the copying density constant). These copying instructions other than that of the paper feed cassette are the standard conditions. However, since each paper feed cassette may be used as the upper or lower cassette, it cannot say the upper cassette is standard. In other words, it may be ineffective to change the instruction of the paper feed cassette in the interrupt copying mode.